Electrical measuring instrument.



S. M. KINTNER.

ELECTRICAL MEASURING INSTRUMENT.

APPLICATION FILED OUT. 3, 1905.

999,800, Patgnted Aug. 8, 1911.

Big. 1. MW

' ATTQRNEY UNITED sra'rns Parana enrich.

SAMUEL KINTNER, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSEELECTRIC & MANUFACTURING COMPANY, A. CORPORATION OF PENNSYLVANIA.

Specification of Letters Patent.

Patented Aug. 8, 1911..

Application filed October 3, 1905. Serial No. 281,136.

To all whom it may concern:

Be it known that I, SAMUELM. KINTNER, a citizen of the United States,and a resident of Pittsburg, in the count-y of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in ElectricalMeasuring Instruments, of which the following-is a specification.

My invention relates to electrical measuring instruments of theelectrostatic type and it has for its object to provide means wherebythe range of utility and the accuracy of operation of such instrumentsmay be greatly increased over instruments heretofore constructed.

Electrostatic instruments usually comprise one or more stationary andmovable vanes that are supported in electrostatic relation to each otherand that are sometimes immersed in an insulating fluid contained withina grounded metallic receptacle in order to increase the efliciency andaccuracy of operation and to enable simplification of the structure andreduction of its dimensicns. It is in combination with such instruments{that I propose to employ my invention which consists in providing oneor more condensers which may be connected in Series circuit with thestationary and movable vanes and in placing the condensers in the sameinsulating fluid and receptacle as contain the vanes of the instrument.Since the drops of potential over condensers which are connected inseries circuit are inversely as the capacities of the condensers, thevoltage existing between the relatively movable members may be adjustedby the inclusion in or the removal from the circuit of the condensers.If a plurality of difi'erently divided scales are provided theinstrumentbecomes adapted to the measurement of a greater range ofvoltages than would be the case if no condensers were employed. Theinstrument may in this manner be constructed to measure comparativelyhigh and low voltages and intermediate voltages and its field of utilitygreatly enlarged.

Figure 1 of the accompanying drawings is a sectional view of aninstrument embodying my invention and Fig. IS a V ew partially in planand partially in section of the instrument shown in Fig. 1.

Movably supportedin an insulating fluid that is contained within ametallic receptacle 2, having a connection to ground at G,

is a conducting member 3 comprising a pair of hollow, cylindrical bodies4 and 5 that are attachedto opposite edges of a vane 6. The member 3 issuspended from a rod 7 by means of a clevis shaped piece 8, and aninsulating rod 9. A hearing 10 is provided for the lower end of the rod7 in an extension 11 of a bushing 12, that is suitably secured in acentrally located aperture in an insulating block 13 which forms thecover of the receptacle 2. A hearing 14: is also provided for the upperend of the rod 7 in the free end of a bracket 15, which is supported onthe upper side of the cover 13 of the receptacle. Opposite ends of aspring 16 are connected respectively to the clevis shaped piece 8 andthe bushing 12, rotation of the movable element 3 from its normal orzero position being opposed by the ten sion thereof. A pointer or index17, that is carried by the rod 7 cooperates'with a plurality ofdifierently calibrated scales 18, 19 and 20 that are provided in anysuitable manner upon the upper side of the insulating cover 13 toindicate-by its angular deflections the forces measured by the instru-Inent.

Mounted upon the under side of the cover 13 are insulating supports 21for a pair of substantially cylindrical shaped vanes 22 and 23 that arearranged with their concave faces opposing each other and in proximityto the movable bodies 4 and 5. The vanes 4 and 5 are also so arrangedwith regard to the vanes 22 and 23 that as the member 3 is moved fromits zero or normal position, the distances between thebodies 4t and, 5and the vanes 22 and 23 decrease at a proper rate in'order that thescales 18, 19 and 20 may be substantially uniform; that is, in orderthat equal divisions thereof may represent equal forces. The insulators21 also support condenser plates 24: and 25, the faces of which arearranged respectively opposite the faces of corresponding condenserplates 26 and 27 that are attached to the lower ends of conducting rods28 and 29, having binding posts 30 and 31 at their upper ends, whichserve as circuit terminals for the instrument. The rods 28 and 29 areinclosed and supported by tubular insulators 32 and 33 which arescrew-threaded in the cover 13. The condenser plates 2 1'and 26 and theplates 25 and 27 maybe electrically connected by means of conducting themeasurement of the highest voltages of which it is capable. The voltageexisting between the vanes 22 and 23 will then be the difierence betweenthe total voltage of the external circuit and the sum of the drops ofpotential between the condenser plates 25 and 27 and between plates 24and 26, the drops of potential between the corresponding condenserplates and between the vanes 22 and 23 being, according to wellunderstood principles, inversely propor-- tional to the electrostaticcapacities of these parts. The voltages corresponding to the actuatingforces will, in the case illustrated, be indicated upon the scale 18.

If it is desired to measure lower voltages than can be accuratelyindicated on the scale 18, one or the other of the conducting blocks and36 should, be lowered so as to short circuit one of the condensers andthe voltages will then be indicated by correspondingly largerdeflections upon the scale 19. In this case, the voltage which existsbetween the vanes 22 and 23 is equal to the difference between the totalvoltage of the circuit and the drop potential over the condenser whichremains in circuit. If it is desired to measure still lower voltages,both of the conducting bloclrs should be lowered so as to render bothcondensers ineffective so that the total voltage of the external circuitmay be impressed upon the vanes 22 and 23. The voltages will then beindicated upon the scale 20.

Since the dielectric strengths of insulating fluids in general areincreased when compressed it may often be found desirable to provide asuitable means wherebycompression may be effected, such, for instance,as a pump 38 that is connected by means of a pipe or tube 39 with thereceptacle 2.

lit should be noted particularly that owing to the employment of theauxiliary condensers the distances between the stationary vanes and themovable body may be diminished and the terms of the scales thereby muchimproved. An important advantage which. pertains to the placing eat theauxiliary condenser plates in the same diseason electric as that inwhich stationary and movable elements of the instruments are immersed isthat no errors may then be introduced in the measurements owing tochanges in frequency and wave form. The grounded metal receptacle alsoserves to pre vent trouble which might arise due to static inductionfrom the condensers to adjacent objects since it is capable of screeningthem from external efiects and keeping them in constant relation at alltimes.

I claim as my invention:

1. An electrical measuring instrument comprising stationary and movablemembers arranged in electrostatic relation, one or more condensersconnected in series circuit therewith, a body of insulating liquid inwhich said parts are immersed, and means for maintaining said liquidunder compression.

2. An electrical measuring instrument comprising stationary and movablemembers arranged in electrostatic relation, one or more condensersconnected in series circuit therewith, means for short-circuiting thecondenser or condensers, an insulating liquid, a containing vesseltherefor and means for maintaining said liquid under pressure.

3. An instrument comprising stationary vanes,-a movable member supportedin elec trost'atic relation thereto, one or more condensers havingterminals connected to the respective stationary vanes and to circuitterminals of the instrument, means for short-circuiting the condenser orcondensers, an insulating liquid, a containing vessel therefor, andmeans for maintaining said liquid under pressure. 7

4:. An instrument comprising stationary vanes, a movable membersupported in electrostatic relation thereto, one or more condensershaving terminals connected to the respective stationary vanes and tocircuit terminals of the instrument, bridging devices and means formoving them into and out of engagement with the condenser electrodes, aninsulating liquid, a containing vessel therefor, and means formaintaining said liquid under pressure.

in testimony whereof, T have hereunto subscribed my name this 29th dayof September, 1905.

SAMUEL M. KTNTNER.

